Transfer of powdered or particulate materials between containers typically involves the use of screw conveyors and similar equipment. This equipment includes heavy duty rotating shafts running in ball, roller or sleeve bearings. These bearings can be easily destroyed through the introduction of the particulate material into the bearings due to the abrasive nature of the material. Even though the bearings are usually running in a liquid or viscous lubricant, such lubricants are easily contaminated with abrasives should they enter the bearing. Such contamination will rapidly destroy such bearings, causing costly shutdown of the transfer equipment for bearing replacement. Further, as the bearings must be immediately replaced to prevent catastrophic failure of the transfer system, the timing of the bearing replacement may prove inconvenient, as in during a sizable material transfer. An improved system would allow for delay in replacing the bearings while a transfer is completed or crews can be conveniently available. A variety of devices and bearing systems have been developed to prevent damage to shaft bearings by abrasive materials.
U.S. Pat. No. 5,908,248, issued to Nisley, discloses a shaft bearing having improved seal arrangement. The seal permits the egress of foreign matter from a bearing area and inhibits ingress of such material which utilizes a lubricant fitting to introduce the lubricant into the bearing area, such that foreign material is purged from the area while inhibiting the ingress of such contaminants into the bearing area. A bearing seal includes a base portion and an annular lip that abuts an inner ring, such that lubricant under pressure in the bearing area may be forced between the seal and the inner ring and out of the bearing area through a gap. The lubricant in the chamber may be forced between the lip and a stamping, such that foreign matter such as moisture and other contaminants cannot pass back in the other direction. The lubricant dam exerts pressure on the lip encouraging the egress of lubricants from the lubricant dam out of the bearing, and thus provides a purging path to remove contaminant material introduced to the bearing.
U.S. Pat. No. 4,776,709, issued to Tooley is directed to a seal for shaft bearings that provides for the bearing assembly to be purged by the outward flowing of lubricant and at the same time the bearing assembly may be protected from the introduction of foreign matter. A housing includes a bearing assembly comprising an outer race and inner race, and two rows of roller bearings. The assembly is lubricated through a fixture. One embodiment includes a V-ring seal which permits the bearing to be purged by the introduction of lubricant from the bearing, and at the same time, prevents the introduction of dirt moisture, and other foreign matter through the seal into the bearing by the seating of the lip on the annular surface of the ring.
U.S. Patent Publication No. 2007/0070806, issued to Swisher is directed to a mortar mixer and trunnion assembly. The seals for the trunnions are particularly adapted for use in mortar mixing drums in which the seals partition a portion of the interior space to define a first chamber for carrying grease and a second interior space which defines a chamber which forms a positive seal to prevent contaminated grease from entering the bearing. A pair of Zerk fittings is used to provide grease to the chambers in order to provide the necessary lubrication for the shaft while preventing contaminated grease from entering the bearing surfaces.
U.S. Pat. No. 6,932,512, issued to Cox et al. is directed to an agricultural rockshaft bearing block structure and wear inserts. The bearing block structure utilizes a two-piece ultra high molecular weight polyethylene wear insert so as to limit the wear between the steel rockshaft and the metallic bearing block. The bearing blocks often include grease fittings for lubrication to reduce the wear, but introduction of contaminating materials into the lubricants often accelerates the wear and it is necessary to purge the contaminants from the rockshaft and bearing block while utilizing UHMW materials to limit the wear.
U.S. Pat. No. 5,188,214, issued to Uttke et al. discloses an end seal for idler roller. The conveyor system includes a plurality of idler rollers journaled for rotation around individual stationary shafts. In order to protect against the entry of contaminants an end seal assembly, including an inner seal member mounted to the roller and an outer seal member mounted to the stationary shaft are provided. The principal feature of the invention is that the idler end seal is adapted for use in conveyor systems that carry materials generating abrasive airborne dust, and thus it is necessary to prevent this abrasive material from entering the bearing areas.
It is an objective of the present invention to provide a system to mount bearings to support rotating shafts for transfer of particulate and abrasive materials. It is a further objective to provide such a system that will prevent contamination and subsequent rapid wear of such shafts by the subject materials. It is a still further objective of the invention to use lubricating materials to prevent unwanted movement of abrasive materials along the rotating shaft and into the bearing. It is yet a further objective to provide a weatherproof and dimensionally stable mounting structure for the bearing and the shaft. Finally, it is an objective of the present invention to provide a back-up bearing surface that is instantly available should the bearing fail.
While some of the objectives of the present invention are disclosed in the prior art, none of the inventions found address all of the requirements identified.